The photon of hard gamma radiation knocks a proton out of $${}_{12}^{24}Mg$$ nucleus to form

t_1/4 can be taken as the time taken for the concentration of a reactant to drop to $$3 \over 4$$ of its initial value. If the rate constant for a first order reaction is K, the t_1/4 can be written as

A schematic plot of $$ln$$ $${K_{eq}}$$ versus inverse of temperature for a reaction is shown below


The reaction must be

In a first order reaction, the concentration of the reactant decreases from 0.8 M to 0.4 M in 15 minutes. The time taken for the concentration to change from 0.1 M to 0.025 M is